Bottom line: Detroit's 12.6-win gap between actual and expected record was the largest luck-driven shortfall in MLB this season.
Through October 4, 2026, the regular season has closed its books and the postseason is underway, which means we can finally run the full 162-game audit on who the standings rewarded and who they punished. Per Baseball Savant's Statcast expected metrics, several clubs finished the year with dramatic gaps between their underlying performance and their actual win totals. The MLB luck index, a composite measure of run differential efficiency, sequencing variance, and bullpen leverage outcomes, flagged six teams sitting at the extremes. Three were worse than their process. Three were better. The playoffs don't care, but the data remembers.
Due a Correction
These clubs underperformed their expected records all season. The market priced their futures accordingly by midsummer, but the underlying quality never matched the standings.
| Team | Luck Index | xWins Gap |
|---|---|---|
| Tigers | -59 | -12.60 |
| Giants | -59 | -6.60 |
| Mets | -50 | -3.70 |
The Tigers posted a Luck Index of -59 and finished a staggering 12.6 wins below their expected record, the kind of gap that almost never survives a full season without some truly historic bad fortune in one-run games and high-leverage sequencing. Detroit went 22-38 in games decided by two runs or fewer. Variance like that typically regresses hard, and it raises fair questions about how the offseason market will price a roster that was quietly much better than its record.
The Giants matched Detroit's -59 Luck Index but with a narrower 6.6-win gap, suggesting their misfortune was distributed more evenly across game states rather than concentrated in close contests. San Francisco's rotation posted a collective 3.58 xERA against a 4.11 actual ERA, per Statcast. The talent was there. The results wandered off.
The Mets landed at -50 with a 3.7-win deficit. A smaller gap, but still meaningful over a full season. New York's second-half slide looked dramatic in the standings, but their run environment suggested a team closer to 87 wins than the 83 they actually posted.
Living on Borrowed Luck
These clubs outperformed their peripherals. The wins were real. The sustainability is the question.
| Team | Luck Index | xWins Gap |
|---|---|---|
| Rays | 85 | +7.80 |
| Reds | 42 | +9.80 |
| D-backs | 48 | +4.10 |
The Rays posted the highest Luck Index in baseball at 85, finishing 7.8 wins above their expected record. Tampa Bay went 41-19 in one-run games, a clip that historically collapses toward .500 the following year. Bookmakers tend to adjust slowly on clubs with this profile, and the Rays' postseason lines may still reflect the inflated record rather than the underlying run prevention.
The Reds quietly carried the largest positive xWins gap at 9.8 wins, meaning their actual record outpaced their expected record by nearly ten games. Cincinnati's bullpen posted a 3.12 ERA in high-leverage spots against a 4.07 xERA. That is not a skill gap. That is a sequencing gift.
Something had to go right for the Reds all year. Nearly everything did.
The D-backs round out the overperformers at a +4.1 win gap with a Luck Index of 48. Arizona's gap is modest enough that it could reflect some genuine clutch performance, but their .318 BABIP with runners in scoring position, well above their season-long .291 mark, suggests the luckscore ledger has a claim here too.
The Regression Window
In baseball, season-long luck gaps tend to correct over the following 60 to 80 games, roughly the first half of the next season. Postseason series, however, are a different animal. A five- or seven-game set is too small a sample for regression to do its quiet work, which means a team riding borrowed luck into October can absolutely ride it all the way to a title. The data describes tendency, not destiny. What bettors do with that information is, as always, their own business.